In wireless transmission, in addition to a short-range system which is a wireless communication system of a short range and presupposes a transmission distance of several meters to several-ten meters, as represented by wireless local area network (LAN), there exists a near-field system which is a wireless communication system that provides services presupposing a very short communication range of several centimeter or less, as represented by near field communication (NFC). There have been an increasing number of opportunities in which these two systems coexist in the same area.
As a method of enabling the coexistence of the two systems, there is a method in which, for example, carrier sense levels of the short-range system and the near-field system are properly set, thereby enabling the coexistence. In addition, there is a method in which, when different systems interfere with each other, an inter frame space set of one of the systems is controlled, thereby enabling the coexistence. Besides, there is a method in which the near-field system estimates an interference of the short-range system and selects control, thereby enabling the coexistence in an identical frequency band in a specific case.